saunders



A. T. SAUNDEHS.

TENNIS BALL. APPUCATION FIL'EU4 DEC. 4, 1919.

Reissuffd Mau'. 30, 1920. 14,832.

Innen/fwn.'

Addso dauzde',

UNITED sTATEs PATENT oEEIoE.

ADDISON T. SAUNDERS, 0F CHICOPEE, MASS & BROS., OF JERSEY CITY, NEW JERSACHUSET'IS, ASSIGNOR TOr A. G. SPALDING' EY, A CORPORATION 0F NEWJERSEY.

TENNIS-BALL.

Specification of Ressued Letters Patent. ReiSSued lVIal. 30, 1920.Original No. 1,287,766, dated December 17, 191.8, Serial No. 247,604,filed .Tuly 31, 1918.

Application for reissue filed December 4, 1919. Serial No. 342,514.

To all whom t may concern Be it known that I, ADDISON T. SAUNDERs, acitizen of the United States, and resident of Chicopee, Massachusetts,have inventedl certain' new and useful Improvements in Tennis-Balls, ofwhich the following is a specification.

IMy invention relates to playing balls for the game of tennis.

The general object of my invention is to produce a tennis ball which,while possessing all the desirable qualities. of the present type as tobehavior in play, will obviate the use of the usual covering of felt andthus avoid the distortion so generally produced in tennis balls in theact of laying on the covers, or by the uneven stretching of the sectionsthereof, as is evidenced by the flat sides which frequently exist, andwhich cause uneven and off direction plays.

Other objects are to secure greater uni- ,formity of character andbehaviorenable greater accuracy of play, increase durability or wearingqualities, make the ball waterproof and washable, render it capable ofbetter retaining the compressed'air, and susceptible of manufacture at a.lower cost than the balls are'now made.

The common type of tennis ball comprises anso-called center consistingof a hollow ball having but a thin wall composed of a vulcanized rubbercompound of such character as to resist undue distention by the .chargeof `compressed air elnployed therein, while possessing the desireddistortability and resiliency under impact which operates in conjunctionwith that of the compressed air, said center having the property ofretaining, in a degree, the air charge, and a cover consisting ofsections of felt cemented to, and sewed together around this center.

Functions of the usual felt cover are to afford a surface which slightlygrips or clings to the ut of the racket in cut shots, aid control, o erby skin friction a certain resistance to the air in flight,` reinforcethe center and give the desired light color.

The felt cover and the cement therefor make up a considerable part ofthe total weight of the finished ball thus limiting the weight, 'andhence the thickness, of the wall of the center admissible under theregulations. l

Aside from the high cost of the material, the employment of a cover offelt involves numerous objectionable features. No thread has been madeor found for stitching together the sections of the cover which hassufficient strength to withstand the harder blows of the racket whenspun to the fineness of size required to avoid bad seams. It iswellknown that when played by strong expert players some stitchesusually break out with a few blows and that the cover is raised at thesepoints, not only being unsightly but affecting unfavorably the action ofthe ball in play.

As will be understood the common tennis center, or a modicatio-nthereof, by increase in' weight to the total Weight desired, orregulation weight for a ball, will not give satisfactory playingqualities without a cover.

In my improved ball the felt cover is omitted and the functions thereofare performed by an outer layer of a rubber compound, of a softercharacter than that of the center and this outer covering while meetingall the requirements in play avoids the obj ections which exist to theuse of the felt covering.

A preferred form of my invention is illustrated in the accompanyingdrawing in which, l

1 indicates a tennis center of the usual character; 2 a layer offiberized rubber com` may be-somewhat closer together and stag-l geredinstead of in rows. They may be made considerably smaller withproportionate spaces between. In practice I may malte them flat bottomedand with sides at an angle of about forty-fve'degrees.

When making a ball in accordance with the above I prefer to rst makeupand vulcanize in a suitable mold a center of the usual compound andcharacter. flate this in the mold if made by the twoJ marking for thesurface of the ball;

I may inf cure of this center from that required for a finished centerto allow for the later cure described below. Y

yThis center is bued in the usual way to prepare it for adhesion of asuitable cement which is next applied. This cement is to cohere thecenter l and the layer of berized rubber compound 2, which I prefer tomake of a nearly pure, gum and sulfur mixture with nely dividedcottonber in as great proportion as practicable. This-berized compound issheeted and then laid upon the center lto form an even layer, orplurality' of layers, either by laying on and cutting with shears toJoin the edges and l gr1 ation of a felt cover.

remove the superfluous stock in the manner Well known to the -art forlaying and joining sheeted stocks,for I may mold the berized stock intothin hemispherical parts and bring two of these Ytogether over thecemented center.

I next superpose a layer of a compound of rubber of a softer and moreyieldable character than that of thecenter, and in applying this layer Imay use the method described .above in connection with applying theberized layer. I next vulcanize `this cover ortion over the center in asuitable mold or a time and at a temperature which does not "impair thecenter. To this end I vmay employ in the compounds of theselayers anorganic accelerator in the usual manner.

yThe layer of a compound of softer character than the center 1 forms aclinging or ping surface for the gut strings of the racket.'

-It will be understood that the somewhat hard or stili' character ofthecenternecessary forvright behavior-does not afford a surface whichcan' seat itself upon the gut of the racket or afford that clinging orgripping effect which isrequired for control. The layerof softer rubberdoes this and thus successfully supplies this function of the feltcover.

The markings upon the surface, .the use of which is optional, furnishthe skin fric- They also contribute in some degree to the gripping orclinging action, upon the racket.

After curing as above, the ball is-cleansed and oo'acted with a whiterubber paint, or

mineralized cement, comprising, preferably v a rubber solution with avolatile solvent and as a pigment litho ne or zinc oxid. This is appliedby ippmg. When' dry this paint 1s fixed by a vaporcure. Y

Instead of making a distinct layer of berized compound 2, I can get thereinforcing i effect of the ber by mixing it into the comppund of thecenter lor of the softer rubr layer 3, or in both, distributing it sothat I require a less proportion in each compound, but I* can get abetter air-retaining effect by the construction rst described.

I may also, as an alternative forthel white rubber paint, mix thewhitening pigments with the soft layer 3, oruse 'a white pigmented comound laid upon the layer 3 before curing, but I get a whiter color byuse of the rubber paint ap lied as described.

I may also lay up, be ore curing, all of the elements, 1, 2 and 3, andcure themA at one cure. AIn this case I use the `accelerator in thecompound for the center 1, and thus get the greater cure required forthat element-omitting the accelerator from the other compound orcompounds.

Other forms of markings for the softer outer layer may be substitutedfor the depressed markings, such as raised markings or pebbling.

It will be understood that'the employment of the layers of rubbercompound, particularly the outer softer rubber layer greatly increasesthe air retaining properties of the ball over that ofl a ball with theusual center and a felt cover.

I may substitute for the layer or layers of berized compound 2 a layeror layers of f-rictioned fabric.

I have made balls which played well without any intermediate ber orfrictioned fabric layer by modifying the compounds and cures to get thenon-distensibility in that way, such ball consisting of the center 1 ofrubber and the covering layer 3 of rubber, these layers being ofdifferent degrees of hardness with the softer outside.

It will be observed that a balll of my construction is built up withoutstitching at any point thereof, one layer being ,superimposed on theother and united integrally therewith by curing. The softer rubberexterior cover is not intended' to function as a means for preventingdistention of the ball,this function being performed by the harder ball,center 1, and when the intermediate-layer is used this functions as they means for holding the ballto size and shape. f

tures mentioned not being included as limitations on the scope of theinvention, which is defined by the following'- claims.

What I claim is: Y

l. A tennis ball comprising a hollow eenter of rubber compound and anouter layer or rubber compound, the latter being softer than thecompound of the center, substantially as described.

2. A tennis ball comprising a hollow center of rubber compound, an outerlayer of rubber compound, softer than that of the hollow center, and anintermediate layer composed of rubber and fibrous material,substantially as described. 3. A tennis ball comprising a hollow-centerof rubber, an outer layer of rubber compound softer than that of thecenter, and a rubber paint coating on the softer exterior layer,substantially as described.

4. A tennis ball comprising a hollow center of rubber compound, an outerlayer of rubber compound softer than that of the center, and anintermediate layer composed of rubber and fibrous material free fromstitching, substantially as described.

5. A tennis ball comprising a hollow cen ter of rubber compound and anouter layer of rubber compound softer than that of the center and havinghigh and low surface portions, substantially vas described.

6. A tennis ball comprising a hollow eenter of rubber compound, an outerlayer of rubber `compound softer than that of the center, and anintermediate layer composed of rubber and brous material free fromstitching, said softer layer havinghigh and low surface portions. r,

7. A hollow tennis ball having a wall composed of rubber and fabric 'andof substantially the ordinary resiliency and thickness of a tennis ballwall, said ball having on its exterior low portions consisting ofdepressions formed in the normal thickness of the said resilient walland distributed over its ent ire surface, substantially as described.

In testimony whereof, I aix my signature.

ADDISON T. SAU NDERS.

